Autoland- "fault protection"

[???pax]

I was listening to EGGW approach a couple of nights back and the pilot of an aircraft that had just become localiser established on 08 informed the controller that he wished to carry out a "practice autoland". The controller acknowledged the request and went on to inform the pilot that there was "no fault protection".

When he was handed over to the tower the tower controller repeated the "fault protection" statement.

Can anyone shed some light on what "fault protection" means in this context?

Kind Regards,
???pax

[Herod]

For autolands for real (i.e. low visibility) there is a requirement to protect the integrity of the Instument Landing System. When an airport goes into "low visibility procedures" they place a restriction on the movement of vehicles within a certain section of the ILS beam, to prevent any distortion. Additionally there is a greater spacing between aircraft on approach, to ensure that the previous aircraft has cleared the sensitive area in good time. One of the reasons for delays when the weather conditions deteriorate. A practice autoland is one being carried out in better weather conditions, usually to keep crews current on the procedure. If the beam is distorted by a moving vehicle or aircraft it is not so critical, as the crew can see the deviation, monitor it and, if necessary, land manually.

[???pax]

Thanks for the informative and speedy response Herod.

[Bally Heck]

There is also a requirement for a back up power supply for the ILS should the mains fail. I think this meay be required for runway lighting too.

[ 19 July 2001: Message edited by: Bally Heck ]

[Allan]

"No fault protection" means that the normal low visibility procedure which includes that the ATC standy diesel power becomes the primary electrical source is not put in to effect.

[Vortex what...ouch!]

How often must pilots fly an autoland (or practice autoland) to stay current? I heard mentioned once a week but can't remember who from.